Days of the Dead
by Jasmine Dragon Teashop
Summary: Time is running out to forge the perfect antivirus against the zombie strain that's consuming the nation. When the one person who can develop the antivirus goes missing, it's up to Katara and the Gaang to rescue them before it's too late. Modern!AU, Zombie!AU.
1. Prologue: Patient Zero

_**Days of The Dead**_

**Rating: Mature. For gore, violence, language, and explicit sexual content, and character death.**

**Pairings: Zutara, Sukka, Taang.**

_**Prologue: Patient Zero**_

* * *

Katara was only sixteen years old when the world ended.

Even now, she can recall the events in perfectly clarity, hear the panicked screams of pain and frantic shouts of the people around her over the rush of her own pulse pounding in her eardrums. Five years to the day, and she can still feel the blood that had sprayed into her eyes as her father put a bullet in the monster that had pinned her to the floor.

She tries not to think about how that monster had been her mother, once upon a time.

**x x x**

They've coined it the B-Virus, and it spreads like wildfire. By the end of the first month, 30% of the United States population has been infected. By the end of the month, Katara's mother is dead and her home has been burned to the ground.

The military tries evacuation, at first, but it fails when the evacuees start to cannibalize one another. They try quarantine next, and those who manage to escape are cut down or experimented on by the government. The CDC releases the results they get from the testing.

It seems the infected lose all capability for emotion, but they can still feel physical sensation.

It seems they are driven by one desire: the hunger for human flesh.

Katara and her family keep under the radar. Hakoda was a police chief, and the first thing he does is teach her and Sokka how to utilize weaponry.

The first time Katara kills one of the infected, he places a hand on her shoulder and looks at her with something akin to pride in his eyes. She throws up in the bushes, unable to think past the fact that the girl she just shot was wearing a shirt with her favorite band name on it.

Five years later, she still remembers the sunken in face, the missing teeth as the girl's lips widened in an 'O' when Katara put a bullet in her brain.

**x x x**

Wiping the sweat from her forehead, Katara focused her breathing and looked straight through her crosshairs, fingers gently squeezing the trigger as she waited for her brother to signal her from the other rooftop. Raids aren't usually her thing; the 21 year old medic usually stuck to making deliveries to the lab or helping out in the infirmary, but Suki had broken a pinky and Katara had been the only one willing to take her place.

Their group consisted of only eighteen people, which was hard to stomach when you remembered that they had started out with close to thirty. It was made up of a ragtag group of survivors from their hometown of Alabaster, Michigan. The home base was an abandoned old warehouse near Lake Laogai that housed an underground network of tunnels. Usually, the safe-house was well stocked, but they had been forced into rationing smaller portions and travelling farther and farther away to find supplies.

Which was why Katara and Sokka had been forced to travel deep into the inner city to find food.

Something flashed in her peripheral vision and she turned slightly, her wide blue eyes zeroing in the flash of light that came from her left…and swore as she saw her brother with a pack on his shoulders and running for his dear life. Switching positions and focusing on the undead who were converging into a horde of rotting flesh and diseases, Katara bit her lip and pulled the trigger, picking them off one by one.

Their bodies drop and their insides spill over the concrete when her bullets hit their mark, but the sounds they make are not human; they are far beyond that.

She ignores the guilt that stirs in her belly. By this time, the recoil is a familiar, welcome ache in her shoulders.

**x x x**

The siblings return to the base successful, Sokka smug at having evaded the horde and coming out clean, without a scratch on him. She stops his ridiculous exaggeration to Suki with a dry comment about how her rifle's magazine was miraculously full at the start of his ridiculous adventure, and empty at the end.

Suki laughs, and Sokka flushes, scowling tightly at her before their father walks into the tunnel they've claimed as a sleeping place. Hakoda waves a hand to silence them from speaking about the raid, and there is a rare smile on his lips.

"There's someone I'd like you all to meet," He states solemnly, the lines on his face lifting, making him seem not so weary, not so tired.

There's something in his tone that tells them not to argue, and the three exchange glances before rising to follow him through the familiar passageways. There are times when Katara feels like a ghost, in these ruins. She hardly ever ventures into the daylight, preferring to stay underground and help the wounded.

Her fingers run softly over the crumbling dirt, and she raises an eyebrow when her father opens the door to the infirmary. Inside, on one of the four cots, there is a old man and a boy.

Blue eyes flicker to the man first; he is old, but there is an air of strength about him that cannot be ignored. Even so, she finds her eyes continually flickering to the boy beside him, entranced by the way he seemed to glow, by the way she could see the blue veins underneath his pale skin.

"Katara," her father starts again. "This is Roku, and Aang."

She waits for him to explain their significance, and ignores the way Sokka and Suki side-eye her, choosing instead to nod at the two males on the cot, curiosity burning in her gaze.

"Aang is patient zero. He's here to seek refuge with us, and Roku is his companion. I think you should show him your work on the serum."

She nods, but focuses on the words that came before. _Aang is patient zero._ Katara feels something blossoming deep within her chest, something she'd thought died out five years ago: _hope._

_Aang is patient zero._

She kneels beside him, a smile on her upturned mouth, and takes his hands in her own. She gazes up into his wide, gray eyes, and thinks: _you will save us all._

Because Aang -_patient zero_- is the only one whose blood holds the secret to immunity from the virus that has consumed their world. And that means she can finally, finally complete the antivirus she's been working on for half a decade. She lets the tears spill over her cheeks and smiles through them.

She squeezes his hands when he returns the smile, and knows deep within that something is about to change.

**x x x**

**A/N: Whoo! Zombie AU! Anyway, patient zero is normally the person who STARTED the virus, but Aang is referred to in this way because it also means the first to be immune from it, as well. We'll get a lot more on their backstories next chapter, and one of my favorite characters will make an appearance! Well. Of sorts, anyway. Criticisms and thoughts would be adored! :)**


	2. Chapter 1: Ashes to Ashes

**Chapter One: Ashes to Ashes**

_Six Months Later_

"It's the only way-"

"_I don't care!_ He deserves a proper funeral," Aang insisted, voice trembling as hot tears ran down his cheeks.

Katara held back a frustrated snarl, opting instead to pinch the bridge of her nose and try not to snap. She took a deep breath and counted to ten before continuing in what she hoped was a softer tone, laying a hand on the young boy's shoulder.

"I understand, Aang, believe me- I do. We both know this is the only way to keep him from rising. You know as well as I do, that twenty four hours after death, all corpses become...re-animated," the medic told him as gently as she could.

Aang's face crumpled and he let out a loud sob, throwing himself into Katara's arms and heaving with every breath. The young woman held him tight within the circle of her arms, stroking her hands over his shaking frame as a gesture of comfort. Her ears strained to hear what Aang was now continuously sobbing into her chest.

"_It's not fair_," he kept saying, and Katara just held him tighter.

She thought about the blood she could never truly scrub from her skin, thought about all the things she can never unsee. Thought about all the patients and friends she's burned and scattered to the wind.

Thought about the warm eyes of her mother before they turned empty and hollow, like her unbeating heart.

_No_, she thought to herself as he wailed in her arms, _It isn't fair at all._

**x x x**

She knows Aang blames himself for Roku's death, but it hadn't been anyone's fault, truly. He doesn't come out and explicitly say it, but Katara is good at reading people and she can see it in his eyes. Sometimes, when their eyes meet, she wonders if he can see the guilt reflected in her own.

They'd been sent out on patrol, to check the perimeters of the small portion of city they'd claimed as their own. The point to these perimeter sweeps were to check if any infected had been caught in their snares, or triggered one of Toph's ingenious mines. A quick smile flitted over her lips when she thought of the newest addition to their humble clan. When Aang and Sokka had been out on a raid, they'd found her in an abandoned apartment complex, making cherry bombs.

Nineteen years old, blind, and with a GED and give-em-hell attitude, Toph Bei Fong was certainly a force to be reckoned with. She was aggressive and caustic by nature, but Katara knew that underneath the snark and sarcastic remarks that Toph was just as scared as the rest of them. At first, everyone had wondered how she had managed to survive on her own (and in the inner city no less, because most of the infected inhabited that area) but the mystery was soon solved when she demonstrated her amazing hearing abilities and her extremely useful skills in the art of arson and bombing.

She'd only been with them for a month or so, but she and Sokka had teamed up to create homemade fragmentation grenades and self-igniting mini fire bombs. Toph had also come up the idea of setting up trip wire mines around the campsite, and when one of them had been triggered, Roku had gone to investigate.

They started to worry when he didn't return with the rest of the patrol.

Hakoda had gone searching for him an hour later, finding him nearly torn to pieces by three of the infected. Katara shuddered as she thought of his gruesome injuries. His skull had been missing large pieces, chunks and ribbons of red flesh laying on the ground beside him. Several fingers had been missing from both his hands, nothing left behind but bloody stumps that had ivory bone sticking out. The stench of rotting flesh had permeated the tunnels for hours after they'd dragged him in.

Aang had completely broken down, refusing outright to burn his old companion and scatter his ashes, which was the only permanent way to ensure he wouldn't rise from the grave. The second you died, or were bitten by one of the infected, it triggered the strain in your blood...and you only had 24 hours before you turned into one of the flesh-eating monsters yourself. Katara had finally convinced him to see reason, telling him Roku wouldn't have wanted to come back and be killed by his former friends.

And now, here they were, standing by the clear, sparkling waters of the lake and putting the last pieces of dry wood they'd found on Roku's makeshift pyre. Aang lit it himself, albeit with trembling hands, and sank to his knees with a cry as the sparks leapt across the wood and his mentor caught fire. The flames flared a brilliant orange, and the rest of the group had stood and paid their respects before wandering back underground.

Katara tried to forget the last time she had done this, placing the body of the woman who had taught her the art of medicine as well as she known how. She stares into the flames, dully wondering who's body she's going to see charred next, and she and Toph stay behind with Aang as he sobs through the sunset.

**x x x**

"What good is it?" He wondered aloud later that night, knees pulled up to his chest as he layed on the cold floor, large gray eyes trained on the ceiling. Katara didn't answer, trying to ignore the way she could still smell the burning flesh from outside.

Toph didn't wait for Aang to clarify.

"What good is what, Twinkletoes?" The blind girl snapped. She hardly ever called anyone by their real names, preferring to use her personalized, often demeaning nicknames instead.

He waved a hand at himself before tracing one of the blue veins under his skin with a trembling finger.

_That's precious blood, Aang. Don't want to waste a drop_, she thinks.

"What good am I?" Aang said lowly, in a voice that was both defeated, and small. "I couldn't even save Roku, how the hell am I supposed to save anyone else? There's no point, _I'm useless_-"

"Listen to me, Aang," Toph snarled, cutting the pale boy off mid sentence.

"We've all lost people important to us. We've all been through some horrible shit."

She paused and let out a bitter laugh, fingers curling into the loose dirt beneath them.

"Hell, we're still going through horrible shit. The world is a fucking shit place. But the point I'm trying to make here is this: we all keep going, don't we? We keep going because we have to. Because we can't afford to be weak, Aang."

Another pause. "_You_ can't afford to be weak. Look, I don't pretend to know much about all that scientific crap Katara spews all the time, but I know that your blood -no one's elses- can maybe save this godforsaken world and if that doesn't motivate you to keep going I should just do us all a favor and put a bullet in your chest right now."

Toph was breathing hard, her glassy emerald eyes somehow managing to zero in directly on the boy across from her, her fists clenched tightly and a scowl on her pretty features. Katara was about to open her mouth to reprimand her for speaking so harshly when she saw Aang look her way and shake his head slightly.

He was sitting up now, nodding slowly while looking at Toph with something akin to gratefulness and awe in his gray gaze. A solemn look stole across his young features, and when he spoke, his tone was burning with renewed conviction.

"You're right, Toph. It's my duty to do whatever is required to help save this world, and I shouldn't sitting here whining over it. I promise- to you, Roku, and the rest of the world- that I'll keep going, no matter what."

A light blush colored the young arsonist's cheeks, but she gave a rare smile and nodded in response, lowering her head and letting her bangs fall over her milky green eyes. The three sat in a comfortable silence for the rest of night, and when Katara breathed in the damp, dank air, she pretended that smoke wasn't still clogging her lungs.

**x x x**

When Katara rose in the morning after another sleepless night, she couldn't shake the feeling that something was off. She tried to ignore the warning clench in her lower belly and frowned, unbinding her hair and shaking her wavy, caramel locks loose of her usual braid. The young medic stripped completely and dove into the lake, hissing at the icy splash of the lake water against her skin. Katara has never minded the cold; she welcomes it, welcomes the way the chill slowly seeps through the layers of flesh and blood to echo through her bones.

The one time she feels _numb, _the one time she feels weightless and free, is when she's underwater.

She almost didn't hear the soft footsteps and muffled groan that came from a feet feet away, but stiffened as the noise came close enough to reach her eardrums, swimming back to the shoreline and wrapping her fingers around the familiarly cool steel of her Glock 17. She doesn't go anywhere without it, and she waits with bated breath, hoping the noise would reveal itself to be her idiot brother ambling around aimlessly.

The breath stalled in her throat when she saw the figure finally come into view, and she scrambled out of the water, all modesty forgotten as she saw one of her closest friends crumple to the ground.

Nearly slipping in her haste, Katara fell to her knees beside the man on the ground, grunting as she had to roll his body -please don't him be dead, oh god, please- over and check him for injury. She let out a sob of relief as she felt his faint pulse, swearing as she noticed the blood that was leaking from what looked like a recently reopened wound on his chest.

"Idiot," she hissed, swearing loudly and slapping his cheek forcefully in a vain attempt to rouse him from unconsciousness. She takes a moment to just look at him, study the familiar handsome features; the dark hair and gleaming gold eyes. Katara smacks him once more and prays he'll wake up.

When that doesn't work, she bites her lip, making the split second decision to run back to the base and get help to move him. A chill runs through her veins when she realizes she doesn't know how long he's been stumbling around the city bleeding; there could be a horde following his blood trail at this very moment.

"Hang on, Lu Ten," Katara whispered softly, running to the lake to haphazardly throw on her robe before making a mad dash into the underground tunnels and praying her friend would be safe without her.

**x x x**

**July 19th, 2008 ATR (after the rapture)**

The first few months are the hardest.

They are running out of supplies, and they are running out of hope. But Katara thrives on adversity, where she has never had to face it before. Early on, she forbids herself from thinking about before- the rest of the world has divided this new era in two: before the rapture, and after. The world is dark, after. No electricity, cities razed to the ground, and the acrid stench of rotting flesh that never fades away.

Hakoda does his best to keep them alive, and they slowly make their way away from the cities and towns, instead deciding to camp out forests and empty back roads, sleeping with one eye open, always open.

In the after, there is no such thing as a ghost town, no such thing as an abandoned, empty city. The people haven't left, they've turned- and there is no saving them after that.

Katara learns this the hard way. It happens when a year has almost passed, when they have travelled almost without pause toward the midwest. There are rumours of a safe haven there, of a place that lies in the mountains and is untouched by the plague of the B-virus.

_Ba Sing Se._

When they arrive, Katara has to admit it the city takes her breath away. Ba Sing Se is surrounded by white capped mountains and an emerald forest range that stretches as far as the eye can see. The city itself lies inside a basin, of sorts, protected from the outside world. Hakoda had gone forth to get a closer look, leaving Katara with a knot of worry in her stomach.

"Maybe that hobo was right after all," Sokka said incredulously, a small smile appearing on his lips.

Katara had turned to her brother with her hands on hips, lips pinched into a tight grimace as she contemplated what could be lying ahead. She was never one for lying to herself, and she knew that in all likelihood, Ba Sing Se was as over-run with the infected as the rest of the nation.

"Right, and _maybe_ your ex-girlfriend turned into the moon," She hissed.

"You never know," was her older brother's quiet reply, and she turned away, nails digging into her palm.

When Hakoda comes back, he doesn't speak. He's bleeding from the temple but silences Katara's cry of concern with a look and holds out his palm for them to peek inside.

His fingers unfold to reveal a white lotus, slightly crushed but safe in his hand.

"I-...I don't understand," his daughter whispers with a frown, running her hands down her ragged jeans in frustration.

Her father turns, his lips turn up in what could either be a grimace, or a smile.

"Tonight, we'll stay with the Order of the White Lotus."

Katara knows better than to ask, so she bites her tongue and begins to wordlessly set up camp, the tension in her shoulders increasing as she roughly unpacks their meager belongings. When Sokka places a hand on her trembling shoulder, some of it drains away at the touch, but when she turns to the darkening sky to look for answers, she finds none.

"How much longer do you think we have to wait?" Sokka asks as night falls around them.

Katara has come to love the night, love the shelter and cover it provides from the horrors of the daylight. When she looks up at the twinkling stars, the same as ever, it's not hard to pretend that this world she lives in is the product of a nightmare and not reality.

Sometimes, things are easier to face when you can't see them as well.

She's about to shrug in response to Sokka's questions when three figures cloaked in black drop from the trees with a thud. Instinct kicks in and her fingers are instantly wrapped around her holster, and if she can just pull out her revolver-

That line of thought stops instantly when the cold steel of a blade is pressed to her flesh.

"I'm not going to hurt you. Come with us," a distinctly masculine voice hissed into her ear, and Katara had to bit down hard on her lip to keep from replying. These must be members of the mysterious Order her father had mentioned earlier.

Sure enough, when she stood and whirled to face him with narrowed eyes, she saw the now familiar symbol etched onto his heavy black cloak. He pulls down the hood, revealing himself as a young man with raven hair tied back in a ponytail, and friendly gold eyes. He bows, and Katara's fingers relax on gun in her fingers, something inside of her instinctively trusting the man in front on her.

"My name is Lu Ten. I'll be escorting you to your quarters at Ba Sing Se. I sincerely apologize for the subterfuge and rough handling...we had to make sure you weren't going to attack us first," He tells her, giving her a look of mild curiosity before turning away.

Hakoda touches his shoulder and they start speaking in low tones, effectively excluding Katara from the conversation.

Katara doesn't like to be excluded.

"So what exactly is this mysterious Order, anyway?" She interrupts loudly.

Lu Ten turns, and his lips quirk upward slowly when he looks at her this time, really looks at her, and she can see in his gaze that he views her as an equal. It causes a pleasant flush to spread across her cheeks, but she holds his gaze steadily as she restraps her holster to her thigh.

"Well," he starts, and his voice is a soft drawl, "You're about to find out."

**x x x**

**Present Day**

Four hours later, and Lu Ten still hadn't woken up.

Katara couldn't help herself from being worried if she tried. He'd sustained multiple, nearly life threatening injuries in the month long trek it took to reach their little campsite. In his sleep, he'd started babbling, and the medic had worriedly checked him for signs of a fever, or signs of the change. But there had been no bite marks on his bruised flesh, so she sighed in relief.

She curls up onto the chair she'd pulled up by his cot and tucks her knees up against her chest. The young woman trained worried blue eyes on the man who was currently unconscious, a small smile appearing on her lips when she thought of everything he'd taught her. Lu Ten and his father, Grandmaster Iroh, were her closest confidants besides Sokka...and now Aang and Toph.

During the two years she had spent in Ba Sing Se, she and Iroh had developed countless antidotes, only to be bitterly disappointed when all of them had failed. But now that they had found Aang, Katara had little doubts that she and the old scientist could perfect their serum once and for all. Gently checking Lu Ten's fresh bandages, Katara leaned back in her chair and fell asleep.

Or at least, tried to. Because only ten minutes after her eyes had closed, Lu Ten let out a scream of terror.

"What is it?" She asked frantically, scrambling to his side and catching one of his thrashing hands with her own.

"K-katara?" He seemed confused, before reality dawned on him. Lu Ten leaned back weakly and offered her a grim smile. "Ah. I see I made it, then."

"Yes," she began cautiously. "You did. Mind telling me what was so important that you traveled on foot to get here?"

Lu Ten's jaw tightens, and Katara's stomach plummets with dread before he speaks.

"My father..." He pauses and swallows. "I failed. Iroh is missing, and the White Lotus has fallen."

His voice breaks, and Katara feels ice run through her veins at his words. _This is bad._

One thought runs through her mind before she shouts for her own father: _This is very, very bad._

**x x x**

**A/N: All the guns mentioned? I've shot them myself, and I think not only are they practical, but they fit Katara well. Ba Sing Se is based off of Jackson Hole, Wyoming. I bet some of you were expecting Zuko, not Lu Ten...but no worries, our favorite prince will show up soon. ALSO. in case anyone was wondering, LU TEN IS ALIVE BECAUSE I LOVE HIM. (And because he has a big role to play!) Next chapter, we find out more about the Order of the White Lotus, and the Gaang plays a little game called search-n-rescue.**

**Plus, I try and keep everyone in character as much as possible, but keep in mind this is going to be a pretty dark story, and I doubt everyone is going to be their normal, cheery selves, when the world has gone to hell around them. Especially Aang. So, I'd love it if you let me know when the characters are getting too OOC, but it is an AU, so I do have a bit of freedom, lol. 3 Review?**


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